Using 3rd party Python modules
Python3.4 in Blender is bundled within Blender. It doesn't share libraries with system's python (see this related post).

So, to use extra libraries you need to install it into /blender/2.72/python/lib/python3.4/.

OR you can remove /blender/2.72/python and Blender will fallback to using the Python installed on the system (however the versions must be compatible).

OR you can specify a folder in the script input of the User preferences:



Note that this folder must contain 3 sub-directories : addons, modules, and startup. So you can install the library in the modules folder.

As Gandalf3 suggested, you can find more information in the wiki here.